1. Field of the Invention
This invention relates to means and a process for reducing exhaust emissions of diesel fuels. More particularly, the invention is concerned with reducing the amount of invisible particulates in diesel engines exhaust emissions. The invention also relates to a method for operating a diesel engine in such a manner that there is produced a minimum of harmful obnoxious exhaust smoke by that engine.
Diesel fuels used in diesel engines give off in the exhaust of the engine particulates which recent tests indicate to be harmful pollutants. These particulates include not only those that exist as visible smoke when the diesel engine is overloaded or when the engine is worn or dirty, but also those that are invisible and emerge from partly loaded clean diesel engines. The Federal Environmental Protection Agency has determined that diesel-powered automobiles emit unacceptably high levels of air pollution and must be reduced to ward off a possible health hazard.
Tests of 10 foreign and domestic cars showed many of the vehicles emitted particulate matter in amounts exceeding the agency's proposed standard for diesel-powered autos.
The proposed standards would allow six-tenths of a gram per mile for 1981 model cars, to be reduced to two-tenths of a gram per mile by the 1985 model year.
2. Description of the Prior Art
The prior art to which this invention relates is aware of coassigned U.S. Pat. Nos. 4,207,078 and 4,222,746.
The first of these describes and claims a diesel engine fuel containing a particulate-suppressing mixture of an alkyl cyclopentadienyl manganese tricarbonyl and an oxygenated compound such as an aldehyde or a ketone. The second patent discloses and claims a diesel fuel containing a particulate-suppressing mixture of a wax oxidate and a fuel soluble organometallic compound.
According to a paper entitled "Diesel Engine Exhaust Emissions and Effect of Additives" by M. S. El Nesa et al., Instr. Mech. Engs. C137/71, pages 156-162, the addition of small percentages of cyclohexane to 40-50 cetane diesel fuels reduces smoke level, CO, formaldehyde and oxides of nitrogen occurring in the exhaust of a diesel engine.